This application is based upon and claims the benefit of priority from the prior Japanese Patent Applications No. 11-173015, filed Jun. 18, 1999; and No. 11-299700, filed Oct. 21, 1999, the entire contents of which are incorporated herein by reference.
The present invention relates to a computer system such as a personal computer and, more particularly, to a computer system capable of setting the processing speed to a processing speed designated by user operation, and a processing speed control method therefor.
In recent years, various portable laptop or notebook type battery-operable personal computers (to be referred to as PCs hereinafter) have been developed. For PCs of this type, high-speed (high-performance) CPUs have been developed. This allows the user to easily obtain a comfortable use environment.
However, a higher-speed CPU requires higher power consumption, increasing the power consumption amount of the whole PC and decreasing the battery operating time.
Recently, in order to save power, a technique for setting the processing speed of the system to a predetermined processing speed designated by user operation has been developed. The processing speed of the system can be set to one of a plurality of speed levels from the highest to lowest speeds by, e.g., intermittently operating the CPU at a predetermined period or switching the operating frequency or voltage of the CPU. Which of speed levels is to be used during the user job period is determined by user""s designation.
However, in a conventional system, the processing speed designated by user operation effectively acts even during a period in which the user cannot actually operate the computer system, for example, during the start or shutdown period of the computer system. For this reason, start or shutdown processing of the computer system requires a long time.
When the CPU speed is switched to the highest speed by user""s designation or another predetermined factor after the CPU operates at a low speed during system start processing, normal operation may not be assured depending on the operating system or drivers. This is because most of operating systems and drivers obtain an absolute time necessary for a device response wait by software using a software loop counter.
More specifically, the operating system or driver calculates and registers in system start processing a time necessary for repetitively executing a specific instruction N times. In actually accessing a device, the repetitive execution number of the instruction necessary for a device response wait is determined using the registered information. If the CPU speed is set, e.g., twice as high as the speed in system start processing, the actual wait time becomes half the expected value even when the specific instruction is repetitively executed the same number of times. To normally operate a device, at least a wait time equal to or longer than the wait time defined by the device must be assured.
Even if system start processing is executed at a CPU speed which is not the highest, and then the CPU speed is increased by user""s designation or another predetermined factor, device operation fails. In some cases, a serious error occurs such that an instruction or data cannot be normally read.
Accordingly, it is an object of the present invention to provide a computer system for implementing high-speed start processing or the like, and a CPU speed control method therefor.
It is another object of the present invention to provide a computer system for improving the reliability of system operation, and a CPU speed control method therefor.
According to one aspect of the present invention, there is provided a computer system comprising: means for designating a user to designate a processing speed of a processor; means for controlling the processing speed of the processor; and means for setting the processing speed by the means for controlling, setting the processing speed to a highest speed during a period for start processing of an operating system for the computer system, and the processing speed to the user-designated speed during a period other than that for the start processing of the operating system.
According to another aspect of the present invention, there is provided a computer system comprising: means for designating a user to designate a processing speed of a processor; means for setting the processing speed of the processor; and means for setting the processing speed by the means for controlling, setting the processing speed to a highest speed during a period for shutdown processing/suspend processing of the computer system, and the processing speed to the user-designated speed during a period other than that for the shutdown processing/suspend processing.
According to still another aspect of the present invention, there is provided a processing speed control method applied to a computer system, comprising the steps of: designating a user to designate a processing speed of a processor; and operating the processor at a highest speed during a period for start processing of an operating system for the computer system, and operating the processor at the user-designated speed during a period other than that for the start processing of the operating system.
According to still another aspect of the present invention, there is provided a processing speed control method applied to a computer system, comprising the steps of: designating a user to designate a processing speed of a processor; and operating the processor at a highest speed during a period for shutdown processing/suspend processing of the computer system, and operating the processor at the user-designated speed during a period other than that for the shutdown processing/suspend processing.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.